1. Field of the Invention
This invention relates to computing systems, and more particularly, to efficient die power management.
2. Description of the Relevant Art
The power consumption of modern integrated circuits (IC's) has become an increasing design issue with each generation of semiconductor chips. As power consumption increases, more costly cooling systems such as larger fans, larger heat sinks and systems to control ambient temperature are utilized to remove excess heat and prevent IC failure. However, cooling systems increase the system cost. The IC power dissipation constraint is not only an issue for portable computers and mobile communication devices, but also for high-performance superscalar microprocessors, which may include multiple processor cores, or cores, and multiple pipelines within a core.
In order to manage power consumption, a chip-level power management system may transfer power credits from a first on-die component to a second on-die component. In such a case, the first on-die component may be operating in a mode corresponding to given normal or high power consumption. In contrast, the second on-die component may have an activity level below a given threshold. In some cases, these on-die components may be coupled to separate voltage planes. Transferring power away from the active second component to the relatively inactive first component may allow the second component to further increase its activity level or maintain its current activity level for a longer duration of time. In such a case, on-chip performance may increase without creating further cooling efforts from the cooling system. However, transferring power to the second on-die component may tax support systems for the second component such as a voltage regulator.
As is well known in the art, a processor is able to dissipate a maximum power, which is larger than a thermal design power (TDP). The TDP is the amount of power that a cooling system can dissipate. Therefore, to prevent failure, a processor typically operates within the TDP value. This TDP value may be used within logic in a component to select an operating mode. For example, an operational voltage and frequency combination may be chosen based at least on the TDP value. Similarly, a voltage regulator is able to supply a peak current, which is larger than a thermal design current (TDC). The TDC is the amount of current supplied for given operating conditions (e.g., normal to high operating conditions). In some cases, the value for the TDC may be insufficient to support increased activity for the second component discussed above where the increased activity is caused by the power transfer. Although on-chip performance may increase by allowing power transfer between components, the cost of modifying the voltage regulator to support a higher TDC is significant.
In view of the above, efficient methods and mechanisms for efficient die power management are desired.